/*
 * HorizontalListView.java v1.5
 * 
 * 
 * The MIT License Copyright (c) 2011 Paul Soucy (paul@dev-smart.com)
 * 
 * Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated
 * documentation files (the "Software"), to deal in the Software without restriction, including without limitation the
 * rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to
 * permit persons to whom the Software is furnished to do so, subject to the following conditions:
 * 
 * The above copyright notice and this permission notice shall be included in all copies or substantial portions of the
 * Software.
 * 
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE
 * WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR
 * COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR
 * OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
 */

package cn.trinea.android.common.view;

import java.util.LinkedList;
import java.util.Queue;

import android.content.Context;
import android.database.DataSetObserver;
import android.graphics.Rect;
import android.util.AttributeSet;
import android.view.GestureDetector;
import android.view.GestureDetector.OnGestureListener;
import android.view.MotionEvent;
import android.view.View;
import android.widget.AdapterView;
import android.widget.ListAdapter;
import android.widget.Scroller;

public class HorizontalListView extends AdapterView<ListAdapter> {

    public boolean                  mAlwaysOverrideTouch = true;
    protected ListAdapter           mAdapter;
    private int                     mLeftViewIndex       = -1;
    private int                     mRightViewIndex      = 0;
    protected int                   mCurrentX;
    protected int                   mNextX;
    private int                     mMaxX                = Integer.MAX_VALUE;
    private int                     mDisplayOffset       = 0;
    protected Scroller              mScroller;
    private GestureDetector         mGesture;
    private Queue<View>             mRemovedViewQueue    = new LinkedList<View>();
    private OnItemSelectedListener  mOnItemSelected;
    private OnItemClickListener     mOnItemClicked;
    private OnItemLongClickListener mOnItemLongClicked;
    private boolean                 mDataChanged         = false;

    public HorizontalListView(Context context, AttributeSet attrs) {
        super(context, attrs);
        initView();
    }

    private synchronized void initView() {
        mLeftViewIndex = -1;
        mRightViewIndex = 0;
        mDisplayOffset = 0;
        mCurrentX = 0;
        mNextX = 0;
        mMaxX = Integer.MAX_VALUE;
        mScroller = new Scroller(getContext());
        mGesture = new GestureDetector(getContext(), mOnGesture);
    }

    @Override
    public void setOnItemSelectedListener(AdapterView.OnItemSelectedListener listener) {
        mOnItemSelected = listener;
    }

    @Override
    public void setOnItemClickListener(AdapterView.OnItemClickListener listener) {
        mOnItemClicked = listener;
    }

    @Override
    public void setOnItemLongClickListener(AdapterView.OnItemLongClickListener listener) {
        mOnItemLongClicked = listener;
    }

    private DataSetObserver mDataObserver = new DataSetObserver() {

                                              @Override
                                              public void onChanged() {
                                                  synchronized (HorizontalListView.this) {
                                                      mDataChanged = true;
                                                  }
                                                  invalidate();
                                                  requestLayout();
                                              }

                                              @Override
                                              public void onInvalidated() {
                                                  reset();
                                                  invalidate();
                                                  requestLayout();
                                              }

                                          };

    @Override
    public ListAdapter getAdapter() {
        return mAdapter;
    }

    @Override
    public View getSelectedView() {
        // TODO: implement
        return null;
    }

    @Override
    public void setAdapter(ListAdapter adapter) {
        if (mAdapter != null) {
            mAdapter.unregisterDataSetObserver(mDataObserver);
        }
        mAdapter = adapter;
        mAdapter.registerDataSetObserver(mDataObserver);
        reset();
    }

    private synchronized void reset() {
        initView();
        removeAllViewsInLayout();
        requestLayout();
    }

    @Override
    public void setSelection(int position) {
        // TODO: implement
    }

    private void addAndMeasureChild(final View child, int viewPos) {
        LayoutParams params = child.getLayoutParams();
        if (params == null) {
            params = new LayoutParams(LayoutParams.FILL_PARENT, LayoutParams.FILL_PARENT);
        }

        addViewInLayout(child, viewPos, params, true);
        child.measure(MeasureSpec.makeMeasureSpec(getWidth(), MeasureSpec.AT_MOST),
                MeasureSpec.makeMeasureSpec(getHeight(), MeasureSpec.AT_MOST));
    }

    @Override
    protected synchronized void onLayout(boolean changed, int left, int top, int right, int bottom) {
        super.onLayout(changed, left, top, right, bottom);

        if (mAdapter == null) {
            return;
        }

        if (mDataChanged) {
            int oldCurrentX = mCurrentX;
            initView();
            removeAllViewsInLayout();
            mNextX = oldCurrentX;
            mDataChanged = false;
        }

        if (mScroller.computeScrollOffset()) {
            int scrollx = mScroller.getCurrX();
            mNextX = scrollx;
        }

        if (mNextX <= 0) {
            mNextX = 0;
            mScroller.forceFinished(true);
        }
        if (mNextX >= mMaxX) {
            mNextX = mMaxX;
            mScroller.forceFinished(true);
        }

        int dx = mCurrentX - mNextX;

        removeNonVisibleItems(dx);
        fillList(dx);
        positionItems(dx);

        mCurrentX = mNextX;

        if (!mScroller.isFinished()) {
            post(new Runnable() {

                @Override
                public void run() {
                    requestLayout();
                }
            });

        }
    }

    private void fillList(final int dx) {
        int edge = 0;
        View child = getChildAt(getChildCount() - 1);
        if (child != null) {
            edge = child.getRight();
        }
        fillListRight(edge, dx);

        edge = 0;
        child = getChildAt(0);
        if (child != null) {
            edge = child.getLeft();
        }
        fillListLeft(edge, dx);

    }

    private void fillListRight(int rightEdge, final int dx) {
        while (rightEdge + dx < getWidth() && mRightViewIndex < mAdapter.getCount()) {

            View child = mAdapter.getView(mRightViewIndex, mRemovedViewQueue.poll(), this);
            addAndMeasureChild(child, -1);
            rightEdge += child.getMeasuredWidth();

            if (mRightViewIndex == mAdapter.getCount() - 1) {
                mMaxX = mCurrentX + rightEdge - getWidth();
            }

            if (mMaxX < 0) {
                mMaxX = 0;
            }
            mRightViewIndex++;
        }

    }

    private void fillListLeft(int leftEdge, final int dx) {
        while (leftEdge + dx > 0 && mLeftViewIndex >= 0) {
            View child = mAdapter.getView(mLeftViewIndex, mRemovedViewQueue.poll(), this);
            addAndMeasureChild(child, 0);
            leftEdge -= child.getMeasuredWidth();
            mLeftViewIndex--;
            mDisplayOffset -= child.getMeasuredWidth();
        }
    }

    private void removeNonVisibleItems(final int dx) {
        View child = getChildAt(0);
        while (child != null && child.getRight() + dx <= 0) {
            mDisplayOffset += child.getMeasuredWidth();
            mRemovedViewQueue.offer(child);
            removeViewInLayout(child);
            mLeftViewIndex++;
            child = getChildAt(0);

        }

        child = getChildAt(getChildCount() - 1);
        while (child != null && child.getLeft() + dx >= getWidth()) {
            mRemovedViewQueue.offer(child);
            removeViewInLayout(child);
            mRightViewIndex--;
            child = getChildAt(getChildCount() - 1);
        }
    }

    private void positionItems(final int dx) {
        if (getChildCount() > 0) {
            mDisplayOffset += dx;
            int left = mDisplayOffset;
            for (int i = 0; i < getChildCount(); i++) {
                View child = getChildAt(i);
                int childWidth = child.getMeasuredWidth();
                child.layout(left, 0, left + childWidth, child.getMeasuredHeight());
                left += childWidth + child.getPaddingRight();
            }
        }
    }

    public synchronized void scrollTo(int x) {
        mScroller.startScroll(mNextX, 0, x - mNextX, 0);
        requestLayout();
    }

    @Override
    public boolean dispatchTouchEvent(MotionEvent ev) {
        boolean handled = super.dispatchTouchEvent(ev);
        handled |= mGesture.onTouchEvent(ev);
        return handled;
    }

    protected boolean onFling(MotionEvent e1, MotionEvent e2, float velocityX, float velocityY) {
        synchronized (HorizontalListView.this) {
            mScroller.fling(mNextX, 0, (int)-velocityX, 0, 0, mMaxX, 0, 0);
        }
        requestLayout();

        return true;
    }

    protected boolean onDown(MotionEvent e) {
        mScroller.forceFinished(true);
        return true;
    }

    private OnGestureListener mOnGesture = new GestureDetector.SimpleOnGestureListener() {

                                             @Override
                                             public boolean onDown(MotionEvent e) {
                                                 return HorizontalListView.this.onDown(e);
                                             }

                                             @Override
                                             public boolean onFling(MotionEvent e1, MotionEvent e2, float velocityX,
                                                     float velocityY) {
                                                 return HorizontalListView.this.onFling(e1, e2, velocityX, velocityY);
                                             }

                                             @Override
                                             public boolean onScroll(MotionEvent e1, MotionEvent e2, float distanceX,
                                                     float distanceY) {

                                                 synchronized (HorizontalListView.this) {
                                                     mNextX += (int)distanceX;
                                                 }
                                                 requestLayout();

                                                 return true;
                                             }

                                             @Override
                                             public boolean onSingleTapConfirmed(MotionEvent e) {
                                                 for (int i = 0; i < getChildCount(); i++) {
                                                     View child = getChildAt(i);
                                                     if (isEventWithinView(e, child)) {
                                                         if (mOnItemClicked != null) {
                                                             mOnItemClicked.onItemClick(HorizontalListView.this, child,
                                                                     mLeftViewIndex + 1 + i,
                                                                     mAdapter.getItemId(mLeftViewIndex + 1 + i));
                                                         }
                                                         if (mOnItemSelected != null) {
                                                             mOnItemSelected.onItemSelected(HorizontalListView.this,
                                                                     child, mLeftViewIndex + 1 + i,
                                                                     mAdapter.getItemId(mLeftViewIndex + 1 + i));
                                                         }
                                                         break;
                                                     }

                                                 }
                                                 return true;
                                             }

                                             @Override
                                             public void onLongPress(MotionEvent e) {
                                                 int childCount = getChildCount();
                                                 for (int i = 0; i < childCount; i++) {
                                                     View child = getChildAt(i);
                                                     if (isEventWithinView(e, child)) {
                                                         if (mOnItemLongClicked != null) {
                                                             mOnItemLongClicked.onItemLongClick(
                                                                     HorizontalListView.this, child, mLeftViewIndex + 1
                                                                             + i,
                                                                     mAdapter.getItemId(mLeftViewIndex + 1 + i));
                                                         }
                                                         break;
                                                     }

                                                 }
                                             }

                                             private boolean isEventWithinView(MotionEvent e, View child) {
                                                 Rect viewRect = new Rect();
                                                 int[] childPosition = new int[2];
                                                 child.getLocationOnScreen(childPosition);
                                                 int left = childPosition[0];
                                                 int right = left + child.getWidth();
                                                 int top = childPosition[1];
                                                 int bottom = top + child.getHeight();
                                                 viewRect.set(left, top, right, bottom);
                                                 return viewRect.contains((int)e.getRawX(), (int)e.getRawY());
                                             }
                                         };

}
